Grayscale Tracking And Gamma Response
Our grayscale and gamma tests are described in detail here.
The default Warm color temp preset on the XB270HU is still a bit cooler than D65, especially at the higher brightness levels. The errors become visible at 60 percent and above. The only way to improve upon it is to adjust the RGB sliders as we've done below.
With a few tweaks and a change in the contrast control, grayscale tracking is now very flat with all errors below two Delta E. It's not quite in the realm of a professional screen but it's close. This is excellent performance.
Here is our comparison group.
Out of the box, the XB270HU comes in just below the three Delta E threshold. While it's a decent average error level, it's mainly supported by greater accuracy at lower light levels. The brighter steps have a visible blue/green tint.
Calibration drops the average error to a very low 1.18dE. Now all brightness levels show a perfect neutral gray tone. The Overlord wins the day here because it requires a software LUT calibration. All the other screens are calibrated with their OSDs.
This is one of the best gamma results we've seen in a while. In looking over all our past data, we can see that IPS has a distinct advantage over TN in gamma tracking. It's not a universal constant; some TN screens show excellent gamma. But nearly all the IPS panels we've measured track extremely well. Not only does it improve the viewer's perception of dynamic range, it helps with color gamut accuracy as well.
Here is our comparison group again.
Gamma doesn't get much tighter than this. A .09 variance is about as close to perfect as we've seen. Even the Overlord Tempest with its LUT calibration can't quite match the XB270HU.
We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.
The average gamma value is 2.15; a little below the line, which means it's a tiny bit too bright. Will you see the difference? We can't and we doubt anyone will. What you're seeing here is gamma tracking with no peaks or dips at all.